The research proposes to detect and study altered immune responsiveness in mice infected with Ascaris suum, Toxocara canis, Trichinella spiralis and Nematospiroides dubius. Alterations in the immune responses will be determined primarily by measuring antibody production to a defined antigenic stimulus. Experiments will be carried out to examine (1) potentiation for reagin and other immunoglobulin classes (2) changes in antibody production in chronic nematode infections (3) alterations of local and systemic responsiveness to oral immunization (4) alterations in the pattern of aging in the immunologic system.